Brake-shoe.



N0. 861,556 PATENTED JULY 30, 1907. J. S. THOMPSON.

BRAKE SHOE. APPLIOATION FILED DE0.12,1'906.

INVENTOR QK Z av Maw M JAMES S. THOMPSON, OF OHIOAGO,, ILLINOIS.

- BRAKE-SHOE.

Specification of Letters Patent.

' Patented July 30, 1907.

Application filed December 12, 1906. Serial no. 347,434..

To all whom it may concern: I

Be it known that 1,-JAMES S. THOMPSON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain newand useful Improvements in Brake-Shoes, of which the followingis a specification.

This invention has particular reference to the construction ofa form of brake shoe which will be suited to ready application to wheels of largely different diameters, and which will promptly wear down to ,a good bearing regardless of the diameter of wheel to which it is applied. 1

Under the practice commonly followed, it is to beobserved that the large variation in diameter of wheel employed both on engine drivers and in the case of car wheels makes it necessary to carry in stock a very large number of different sizes of brake shoes to fit these various sizes of wheels, the number of varying sizes required in some instances, on the same type of shoe, being as many as fourteen, for example. It is further known in the art that with a brake shoe of a small radius of curvature on its face, if application of such shoe be made to a wheel of large diameter it will touch and wear only on the points, rendering it liable to be broken in the middle, or if not causing breakage. resulting in insufficient frictional engagement until it has worn down to a reasonably good bearing, while on the other hand, use of the shoe made with a large radius of curvature, upon a Wheel of small diameter, will cause the shoe to have a bearing at the middle only, which will not give sufiicient frictional rubbing action, and also tends to weaken the shoe. at the center before it is 'worn down materially.

The primary object of my invention is the provision of a construction of brake shoe which will cover a wide range of sizes in wheel diameters and cut down matcrially the number of parts necessary to he carried in stock. I

In carrying out my invention I follow the plan indicated in the'accompanying drawing, wherein Figure 1 is a diagrannnatic representation of a standard large size, say a seventy-nine inch driver wheel, and

Figure 2 is a diagrammatic representation of a smaller wheelsay a fifty-four inch driver wheel, both of the Wheels-in question having my improved form of shoe applied to the same.

enty-nine in ch wheel.

Referring-to the construction of shoe marked S, it will be seen that the central part of the base of the shoe is made of a radius of curvature of a diameter about the same as the diameter of the small sized wheel, while the outer portion for about a quarter'of the length of the shoe from each end of the same is made of a larger radius of curvature, enough for example, to fit the sev- It will be seen on examining the application of the shoe S to the large wheel marked A in the drawing. that the outer ends of the shoe face indicated by the latter-a constitute practically one-halfof the bearing surface of the shoe which will have engagement Willi the large wheel when first applied, and that after a reasonable amount of wear, the smaller curvature of the portion of the shoe marked b will be eliminated, and the entire bearing surface of the shoe will come into contact with the large wheel. I

On the other hand, if the shoe is applied to a small wheel, it will have at the outset, at least 50% bearing surface in the curvature indicated by the letter (I having the same radius of curvature as that of the small wheel, and on a few applications of the brake the wear of the shoe will eliminate the variation in the curvatures of the central and outer portions-of the shoe, so that it will have a bearing along the full length of the shoe.

It is obvious that the invention above described with reference to the curvatures employed, or the particular arrangement of the same may he modified materially without departing from the spirit of my invention, and I do not desire tobe restricted in detail, therefore, to the particular dimensions'or arrangement shown.

Having thus described my invention and illustrated its use, what 1 claim as new and desire to secure by Letters Patent, is the following:

1. brake shoe having a pLurz'llity of curved surfaces on its wearing face to render it adaptable to wheels of different diameters. substantially as described.

2. A brake shoe having the middle portion of its wearing: face fornzcd otn certain predetermined curvature, and the outer ends of the wearing face of a curvature of lzu'cer radius. substantially as described.

In testimony whereof I have hereunto signed my name in the presence of the two subscribed witnesses.

JAMES S. THOMPSON.

Witnesses PAH. (huu'nx'rnn. .TAnr-zs NICHOLAS LORENZ. 

